Barcelona's new signing Zlatan Ibrahimovic poses with his shirt during his official presentation. Photograph: Josep Lago/AFP/Getty Images

Zlatan Ibrahimovic last night completed his £57m (¤66m) move from Internazionale to Barcelona claiming he had become "fed up" with the "stress" of playing in Serie A.

Barcelona confirmed they had paid ¤46m for the Sweden striker but that his fee is effectively ¤20m higher because Samuel Eto'o, whom they valued at that amount, has moved in the opposite direction as part of the transfer. Alexander Hleb was also included in the deal, with the former Arsenal midfielder joining Jose Mourinho's side on a year's loan.

Ibrahimovic has signed a five-year contract with the Spanish champions and, speaking to Tuttomercatoweb.it yesterday, made clear his delight in swapping San Siro for the Camp Nou. "When did I start thinking about moving somewhere else? In December, before Christmas," said the 27-year-old. "The more I saw Barcelona play, the more I wanted to leave.

"I was fed up of Italy, of Milan, of your football. You play badly, there's too much stress. I needed something else."

Barça's new striker has pledged to match the achievements of the man he replaces at the club. "Eto'o is part of the history book of this club and he will always be a hero here," said Ibrahimovic of the Cameroon forward who scored 130 goals for Barcelona and helped the side to a string of titles. "I have not come to replace Eto'o – I am somebody different, somebody new, but I will try to achieve as much as Eto'o did, or even more."

The forward has spent the last three seasons at Inter after moving from Juventus and last season scored 25 goals for the Nerazzurri, more than any other player in Serie A. Ibrahimovic's now former manager is adamant, though, that his services will not be missed by the Italian champions.

"We have lost a top player but we have taken another one," said Mourinho. "If Ibra is worth €50m, Eto'o is not worth 49. Inter has done great business.

Eto'o, who has also signed a five-year contract, is also positive about his move to Italy following five years at Barcelona, during which he helped the Spanish club to two Champions League titles and scored in May's 2-0 final victory over Manchester United.

"I made history at Barcelona but that history is finished now," said the 28-year-old. "A new story begins at Inter, I'm starting from scratch, I want a new adventure and I hope everything goes well."

Inter will have the chance to buy Hleb for an initial ¤10m once his season-long loan spell is concluded.